In a prior art telecommunication switching system comprising a plurality of switching nodes, each switching node requires predefined knowledge of the numbering plan of the telecommunication switching system and also how the switching nodes are interconnected. An example of such a system is the public telephone network in the United States. Within the United States, the telephones are grouped in terms of area codes, and within each area code the telephone numbers are further grouped by the first three digits of the telephone number. The telecommunication system itself involves tandem switching systems and central office switching systems. Each central office system is responsible for groups of telephone numbers with each group being specified by the first three digits of the telephone number. This hierarchy of telephone numbers (also referred to as the dialing plan hierarchy) is modeled after the hierarchy of switching nodes, e.g. central offices. Within each central office, the routes to be utilized to reach area codes or other groups of telephone numbers is predefined at system initialization or during system operation by the actions of a system administrator. With this predefined information, a central office can easily determine the communication path to route a telephone call from one of its own telephones to the telephone of another central office even though that central office may be located hundreds of miles away. Within the long distance network, a call may take different routes, but each of these routes is predefined for the switching systems.
In prior art packet switching systems, it is known to allow switching nodes to determine their own path through the packet switching system. U.S. Pat. No. 4,081,612 discloses a system where each switching node transmits multiple packets in order to find a route to a destination switching node. This is commonly referred to as broadcast routing.
These prior art methods suffer from many problems. With respect to prior an telecommunication switching systems, the major problem is the inflexibility in allowing the movements of numbers from one geographical location to another. Whereas this can be accommodated, the databases required to maintain the location of various telephone numbers would be enormous. With respect to the broadcast methods used by the packet switching system or any other type of technique which relies solely on the address for finding the destination, these types of methods absorb a large amount of communication bandwidth within the packet switching system as well as place a large real time load on each packet switching node.